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<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <title>Document</title>
        <style>
            *{
                margin: 0px;
                padding: 0px;
                list-style: none;
            }
            div{
                width: 520px;
                height: 280px;
                margin:100px auto;
                position: relative;
                overflow: hidden;
            }
            ul{
                width: 9999px;
            }
            ul li{
                float: left;
            }
            ol{
                position: absolute;
                bottom:10px;
                left: 50%;
                /* translateX设置百分比，参照物是当前标签的宽度 */
                transform: translateX(-50%);
            }
            ol li{
                width: 10px;
                height: 10px;
                border-radius: 50%;
                background:white;
                float: left;
                margin:0px 4px;
                cursor: pointer;
            }
            span{
                position: absolute;
                top:50%;
                transform: translateY(-50%);
                background:lime;
                cursor: pointer;
            }
            span:nth-of-type(1){
                left: 10px
            }
            span:nth-of-type(2){
                right: 10px
            }
            .current{
                background: #f60;
            }
        </style>
    </head>
    <body>
        <div id="wrap">
            <!-- 引入图片 -->
            <ul id="box">
                <li><img src="images/pic.jpg" alt=""></li>
                <li><img src="images/pic1.jpg" alt=""></li>
                <li><img src="images/pic2.jpg" alt=""></li>
                <li><img src="images/pic3.jpg" alt=""></li>
            </ul>
            <!-- ol>li一般引入有序的内容，实现小圆点 -->
            <ol id="list">
                <li class="current"></li>
                <li></li>
                <li></li>
                <li></li>
            </ol>
            <!-- 左右 -->
            <span class="left" id='left'>左</span>
            <span class="right" id='right'>右</span>
        </div>

        <script>
            // 获取标签
            var left=document.getElementById('left');
            var right=document.getElementById('right');
            var box=document.getElementById('box');
            var wrap=document.getElementById('wrap');
            var list=document.getElementById('list').children;
            var num=0;
            var timer;
            // 把重复的代码封装起来
            function fn(){
                timer=setInterval(function(){
                    num++;
                    if(num>3){
                        num=0
                    }
                    for(var j=0;j<list.length;j++){
                        list[j].className='';
                        }
                        list[num].className='current';
                   
                    n=-520*num;
                    box.style.transform='translateX('+n+'px)'
                },1000)
            }

            // 使用函数相当于执行函数体代码
            fn()
            // 鼠标移入mouseenter
            wrap.onmouseenter=function(){
                // 停止定时器
                clearInterval(timer)
            }
            // 鼠标移出mouseleave
            wrap.onmouseleave=function(){
                fn()
            }
            for(var i=0;i<list.length;i++){
                list[i].index=i;
                list[i].onclick=function(){
                    
                    
                    for(var j=0;j<list.length;j++){
                        list[j].className='';
                    }
                    this.className='current';
                    num=this.index;
                    n=-520*num;
                    box.style.transform='translateX('+n+'px)'
                }
            }

            right.onclick=function(){
                num++;
                    if(num>3){
                        num=0
                    }
                    for(var j=0;j<list.length;j++){
                        list[j].className='';
                        }
                        list[num].className='current';
                   
                    n=-520*num;
                    box.style.transform='translateX('+n+'px)'
            }
            left.onlick=function(){
                num++;
                    if(num>3){
                        num=0
                    }
                    for(var j=0;j<list.length;j++){
                        list[j].className='';
                        }
                        list[num].className='current';
                   
                    n=-520*num;
                    box.style.transform='translateX('+n+'px)'
            }

        

        </script>
    </body>
</html>